While the IP telephony market heats up, thermometers are literally spiking in some wiring closets and computer rooms where VoIP and power-over-Ethernet (PoE) gear is being installed, users say.

Equipment density and overheating are constant issues for data center managers; beating the heat is also becoming a top-mind concern for network and telecom staff deploying gear in wiring closets, as PoE and VoIP equipment are set up in places that once just housed lower-power switches, cooler hubs and patch panel racks.

"Power in general has been our Achilles heel in our [IP telephony] deployment," says John Haltom, network director at Erlanger Health Systems, a southeast regional HMO in Chattanooga, Tenn.

Achilles heel might overstate it, as Erlanger has deployed over 1,500 IP phones in production, both wired and wireless, running off of a Nortel Communication Server 1000 IP PBX. To support IP telephony, Haltom and his staff installed PoE switches in wiring closets to light up the phones, and uninterruptible power supply (UPS) equipment to allow switches to run during a power outage.

These redundancy and power requirements challenged the healthcare organization's IT staff, which supports one 112-year-old hospital.

"Trying to retrofit areas that are already cramped with larger PoE switches, larger UPSes," was the challenge, Haltom says. "By the way, all that gear generates more BTUs, so you have to upgrade the AC units in those closets."

By most measures, the biggest heat-boosters in wiring closets are the PoE switches, which do double duty in transporting Ethernet traffic, and acting as AC power supplies for all IP phones and other PoE-capable gear plugged into the devices powered ports. For example, Cisco's non-PoE 24-port Catalyst 3750 LAN switch generates around 176 BTUs of heat per hour; add the PoE option, and the switch heats up to 534 BTUs. Add in a standard UPS that dissipates 80-100 BTUs, and you've more than tripled the heat output in just one wiring closet in order to support IP telephony. Similarly, Nortel's 24-port Switch 420-T heats up to 220 BTU; its PoE-capable Switch 460-24T-PWR is more than double that.

Planning for how this gear will be cooled off and kept safe should not be an afterthought, experts say.